Port derive empty enum to master (#66)

* release parity-codec v3.2

* impl skip fields and variants (#58)

* impl skip variants

* impl skip on fields

* reorganize code

* in code rename

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* in code rename

* code refactor

* refactor: variant filter

* new version of derive (#61)

* release codec-v3.3 that forward derive-v3.2 (#63)

* Implement derive for empty enums

* Bump version of parity-codec-derive to 3.3

* Fixes test

Cargo.lock

@@ -15,17 +15,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "parity-codec"
-version = "3.1.0"
+version = "3.3.0"
 dependencies = [
  "arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec-derive 3.1.0",
+ "parity-codec-derive 3.3.0",
  "serde 1.0.88 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.88 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "parity-codec-derive"
-version = "3.1.0"
+version = "3.3.0"
 dependencies = [
  "proc-macro-crate 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.27 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

 [package]
 name = "parity-codec"
 description = "Lightweight, efficient, binary serialization and deserialization codec"
-version = "3.1.0"
+version = "3.3.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 repository = "https://github.com/paritytech/parity-codec"
@@ -11,11 +11,11 @@ edition = "2018"
 [dependencies]
 arrayvec = { version = "0.4", default-features = false, features = ["array-sizes-33-128", "array-sizes-129-255"] }
 serde = { version = "1.0", optional = true }
-parity-codec-derive = { path = "derive", version = "3.1", default-features = false, optional = true }
+parity-codec-derive = { path = "derive", version = "3.3", default-features = false, optional = true }
 
 [dev-dependencies]
 serde_derive = { version = "1.0" }
-parity-codec-derive = { path = "derive", version = "3.1", default-features = false }
+parity-codec-derive = { path = "derive", version = "3.3", default-features = false }
 
 [features]
 default = ["std"]

derive/Cargo.toml

 [package]
 name = "parity-codec-derive"
 description = "Serialization and deserialization derive macro for Parity Codec"
-version = "3.1.0"
+version = "3.3.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 edition = "2018"

derive/src/encode.rs

@@ -208,6 +208,11 @@ fn impl_encode(data: &Data, type_name: &Ident) -> TokenStream {
 				).to_compile_error();
 			}
 
+			// If the enum has no variants, we don't need to encode anything.
+			if data_variants().count() == 0 {
+				return quote!();
+			}
+
 			let recurse = data_variants().enumerate().map(|(i, f)| {
 				let name = &f.ident;
 				let index = utils::index(f, i);

tests/mod.rs

@@ -454,3 +454,14 @@ fn recursive_variant_2_encode_works() {
 	let val: Recursive<u32, i32, u32> = Recursive::default();
 	val.encode();
 }
+
+#[test]
+fn encode_decode_empty_enum() {
+	#[derive(Encode, Decode, PartialEq, Debug)]
+	enum EmptyEnumDerive {}
+
+    fn impls_encode_decode<T: Encode + Decode>() {}
+	impls_encode_decode::<EmptyEnumDerive>();
+
+	assert_eq!(EmptyEnumDerive::decode(&mut &[1, 2, 3][..]), Err("No such variant in enum EmptyEnumDerive".into()));
+}